In the state of art, there are several types of contactors, with numerous arrangements of the connections regions. The most part of contactors of the market houses the electromagnet in the lower part of the contactor, this way the command terminals are disposed in the same region due the practicability and cost reduction to perform the connection. Above that, the power region and more above the region of the auxiliary terminals that can be integrated or modular in their constructive form.
The contactor presented in the U.S. Pat. No. 4,006,440, shows a constructive disposal wherein the electromagnet is arranged in the lower part of the contactor and the command terminals are arranged in a region above the coil to ease the interconnection with other dispositive, particularly an overload relay. The U.S. Pat. No. 3,949,333, complements the mentioned patent, showing a side mounting auxiliary contact block that is connected to the contactor and activated by cams. The auxiliary terminals also are arranged in a region above the power contacts and the coil.
The patent EP1051718 granted in October 2005 and modified in October 2012, describes a contactor with the electromagnet in the lower part, wherein the disposal of the terminals is done using planes. Given that the power terminals plane is above the electromagnet and above that, exists also another plane that includes the command terminals and the auxiliary terminals, wherein, they are at the same plane and disposed side by side, sequentially starting from one side of the contactor. This disposition of the terminals grouped in one extremity of the contactor makes difficult to distinguish the command terminals from the auxiliary terminals.
In another way, there is the patent EP2023364, where is described a contactor with the electromagnet in the lower part. Above the electromagnet is the power connection area and above that two areas disposed side by side, being one used for the command terminal and another slightly more elevated, used for the auxiliary terminals, where this different elevation of areas are intended to distinguish the terminals.
Additionally, according to the description of the U.S. Pat. No. 8,159,321, the command terminals and auxiliary terminals are disposed uniformly spaced and distributed along the frame, to favor the assembly.
The U.S. Pat. No. 3,639,866, describes an electromagnetic relay and a relay-adder combination with a constant actuating force. This relay has a coil at its lower part; above the coil a region for the fixed contacts and above the fixed contacts there is a region for the coil terminals.
It is possible to see that since a long time there is a concern to distinguish connection terminals to prevent incorrect wiring.